2018-11-05 08:00:49

by Boris Brezillon

Subject: [PATCH v2] mtd: sa1100: avoid VLA in sa1100_setup_mtd

Enabling -Wvla found another variable-length array with randconfig
testing:

drivers/mtd/maps/sa1100-flash.c: In function 'sa1100_setup_mtd':
drivers/mtd/maps/sa1100-flash.c:224:10: error: ISO C90 forbids variable length array 'cdev' [-Werror=vla]

Dynamically allocate the cdev array passed to mtd_concat_create()
instead of using a VLA.

Reported-by: Arnd Bergmann <[email protected]>
Signed-off-by: Boris Brezillon <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Olof Johansson <[email protected]>
---
Changes in v2:
- Allocate cdev dynamically instead of having a fixed-size array

Hello,

I'm planning to queue this patch to the mtd/fixes PR. Arnd, Kees, feel
free to add your R-b.

Regards,

Boris
---
drivers/mtd/maps/sa1100-flash.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/maps/sa1100-flash.c b/drivers/mtd/maps/sa1100-flash.c
index 784c6e1a0391..fd5fe12d7461 100644
--- a/drivers/mtd/maps/sa1100-flash.c
+++ b/drivers/mtd/maps/sa1100-flash.c
@@ -221,7 +221,14 @@ static struct sa_info *sa1100_setup_mtd(struct platform_device *pdev,
info->mtd = info->subdev[0].mtd;
ret = 0;
} else if (info->num_subdev > 1) {
- struct mtd_info *cdev[nr];
+ struct mtd_info **cdev;
+
+ cdev = kmalloc_array(nr, sizeof(*cdev), GFP_KERNEL);
+ if (!cdev) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
/*
* We detected multiple devices. Concatenate them together.
*/
@@ -230,6 +237,7 @@ static struct sa_info *sa1100_setup_mtd(struct platform_device *pdev,

info->mtd = mtd_concat_create(cdev, info->num_subdev,
plat->name);
+ kfree(cdev);
if (info->mtd == NULL) {
ret = -ENXIO;
goto err;
--
2.17.1

2018-11-05 08:13:33

by Boris Brezillon

Subject: Re: [PATCH v2] mtd: sa1100: avoid VLA in sa1100_setup_mtd

On Mon, 5 Nov 2018 08:58:35 +0100
Boris Brezillon <[email protected]> wrote:

> Enabling -Wvla found another variable-length array with randconfig
> testing:
>
> drivers/mtd/maps/sa1100-flash.c: In function 'sa1100_setup_mtd':
> drivers/mtd/maps/sa1100-flash.c:224:10: error: ISO C90 forbids variable length array 'cdev' [-Werror=vla]
>
> Dynamically allocate the cdev array passed to mtd_concat_create()
> instead of using a VLA.
>
> Reported-by: Arnd Bergmann <[email protected]>
> Signed-off-by: Boris Brezillon <[email protected]>
> Cc: Kees Cook <[email protected]>
> Cc: Olof Johansson <[email protected]>
> ---
> Changes in v2:
> - Allocate cdev dynamically instead of having a fixed-size array
>
> Hello,
>
> I'm planning to queue this patch to the mtd/fixes PR. Arnd, Kees, feel

^ I meant branch,
not PR, but this patch should also be part of the 4.20-rc2 fixes PR.

> free to add your R-b.
>
> Regards,
>
> Boris
> ---
> drivers/mtd/maps/sa1100-flash.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/maps/sa1100-flash.c b/drivers/mtd/maps/sa1100-flash.c
> index 784c6e1a0391..fd5fe12d7461 100644
> --- a/drivers/mtd/maps/sa1100-flash.c
> +++ b/drivers/mtd/maps/sa1100-flash.c
> @@ -221,7 +221,14 @@ static struct sa_info *sa1100_setup_mtd(struct platform_device *pdev,
> info->mtd = info->subdev[0].mtd;
> ret = 0;
> } else if (info->num_subdev > 1) {
> - struct mtd_info *cdev[nr];
> + struct mtd_info **cdev;
> +
> + cdev = kmalloc_array(nr, sizeof(*cdev), GFP_KERNEL);
> + if (!cdev) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> /*
> * We detected multiple devices. Concatenate them together.
> */
> @@ -230,6 +237,7 @@ static struct sa_info *sa1100_setup_mtd(struct platform_device *pdev,
>
> info->mtd = mtd_concat_create(cdev, info->num_subdev,
> plat->name);
> + kfree(cdev);
> if (info->mtd == NULL) {
> ret = -ENXIO;
> goto err;

2018-11-06 13:14:55

by Boris Brezillon

Subject: Re: [PATCH v2] mtd: sa1100: avoid VLA in sa1100_setup_mtd

On Mon, 5 Nov 2018 08:58:35 +0100
Boris Brezillon <[email protected]> wrote:

> Enabling -Wvla found another variable-length array with randconfig
> testing:
>
> drivers/mtd/maps/sa1100-flash.c: In function 'sa1100_setup_mtd':
> drivers/mtd/maps/sa1100-flash.c:224:10: error: ISO C90 forbids variable length array 'cdev' [-Werror=vla]
>
> Dynamically allocate the cdev array passed to mtd_concat_create()
> instead of using a VLA.
>
> Reported-by: Arnd Bergmann <[email protected]>
> Signed-off-by: Boris Brezillon <[email protected]>
> Cc: Kees Cook <[email protected]>
> Cc: Olof Johansson <[email protected]>

Queued to the mtd fixes branch.

> ---
> Changes in v2:
> - Allocate cdev dynamically instead of having a fixed-size array
>
> Hello,
>
> I'm planning to queue this patch to the mtd/fixes PR. Arnd, Kees, feel
> free to add your R-b.
>
> Regards,
>
> Boris
> ---
> drivers/mtd/maps/sa1100-flash.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/maps/sa1100-flash.c b/drivers/mtd/maps/sa1100-flash.c
> index 784c6e1a0391..fd5fe12d7461 100644
> --- a/drivers/mtd/maps/sa1100-flash.c
> +++ b/drivers/mtd/maps/sa1100-flash.c
> @@ -221,7 +221,14 @@ static struct sa_info *sa1100_setup_mtd(struct platform_device *pdev,
> info->mtd = info->subdev[0].mtd;
> ret = 0;
> } else if (info->num_subdev > 1) {
> - struct mtd_info *cdev[nr];
> + struct mtd_info **cdev;
> +
> + cdev = kmalloc_array(nr, sizeof(*cdev), GFP_KERNEL);
> + if (!cdev) {
> + ret = -ENOMEM;
> + goto err;
> + }
> +
> /*
> * We detected multiple devices. Concatenate them together.
> */
> @@ -230,6 +237,7 @@ static struct sa_info *sa1100_setup_mtd(struct platform_device *pdev,
>
> info->mtd = mtd_concat_create(cdev, info->num_subdev,
> plat->name);
> + kfree(cdev);
> if (info->mtd == NULL) {
> ret = -ENXIO;
> goto err;